steve morris has billet LS,s called sml i think they peak at 3500hp his smX is bigblock based billet and good for up to 5000hp these drag and drive guys are stuffing these into pro mod street legal cars then driving a few hundred miles at night to race at the next track its pretty nuts! ck out sick week it just ended but was pretty neat to follow, six second runs and over 250 mph one went 270 this year even a tesla showed up with a bigblock turbo combo it looked pretty sharp if you watch steves video past the middle i,m impressed with how the anodizing is done.

I think those events could give some useful information to boat guys on endurance cam setups. Although they won’t be running sustained high rpm very long.

You have quite a few badass engines!

How many hours do you plan to go before freshening the top ends? Assuming double that and do a full rebuild?

I think Ilmor is making the highest HP production LS engine built specifically for offshore boats. Wonder what a simple Whipple tune could push that engine to:

https://pokerrunsamerica.com/ilmor-m...rmance-engine/

That is pretty much the same power lever offered by marine power and KEM (Kodiac). I have talked with marine power and KEM, the base motor is designed and built by G.M.

Then the vendors do the closed cooling, exhaust and what not. Marine power even told me that they then had G.M. do the EPA testing for them.

I do not know if the IMOR is the same base motor but seems like it may since the specs seem very similar. Way better looking.

Here is the link to G.M. site, KEM even uses some of the same info and video on theirs.

https://poweredsolutions.gm.com/products/lt4-engine/


EDIT:

Just read the linked article,

Yeah, for me personally, the Ilmor package seems more like something powerboaters would want in their engine compartment when the hatch opens. Better looking package with CMI headers, etc..... Not to mention, Ilmor has a good name in the hi-perf offshore market.

Definitely

So, as the only one I know of that has actually done this here is the main thing I can tell you:

Most any boat was designed to have the weight of a BBC. I too was thinking lighter is better, but it's not always. CG is a huge factor to making a hull run correctly. We installed one of my twin turbo engines in a 27 Daytona and it needed lots of trim to lift the bow, so we added weight to the back of the boat and it ran better. Installed two of them in a staggered 42 Fountain...same deal. It wouldn't carry the nose without over trimming. Installed two into my 47 staggered vee, and it took 1,200lbs to make the boat sit on the pad and not bow steer. I'm saying this to illustrate the point that it can be done, but all variables have to be considered.


With regard to performance:

My engines preform very well, and i have put them up against big blocks and always been impressed with how they stack up. BSFC and BSAC numbers are better, the boats all docked as well as a boat with a big block, and the power comes on just like a SC BBC. I'm in the process of outfitting my engines with larger turbine housings to reduce the drive pressure and gain some HP up top, but here is what my current power levels look like.

11PSI 830HP/750TQ 89 octane
15PSI 900HP/830TQ 89 octane
20PSI 1000HP/890TQ 89 octane


I have some tall deck LSX blocks in the shop I bought a few years ago, and I was considering building some 440's out of them and using some larger turbos, but I'm conflicted about doing it. Mainly due to the fact that we will be looking at 1,800-2,500 HP with that set up, and that would need to go into a large hull and again starting from scratch on rigging an CG. Maximum effort doesn't even begin to describe what it takes to build, and dress a package like that with little support from the industry. When you consider that you can build the same power out of a big block for the same or less money and less effort the only thing left to drive you to build it is the "cool factor". I'm not saying anything for or against the LS platform, just sharing my anatomical experience.

Precision, really great post that elevates the LS base knowledge.

LS BSFC/BSAC, where do you figure they benefit compared to a modern head/chamber BBC?

The CG factor is a big one for me, I may end up using an extension box to move weight aft.

The benefit is efficiency. Primarily, when it comes to the pounds of air needed to make one HP. That is why we can run smaller blowers and turbos on a LS than a BBC relative to the displacement. Generally speaking a BBC need 1 LB of air to make 6HP where as a LS can make high 7's almost 8 per lb of air. It's a shame we cannot utilize a 4 valve per cylinder wedge chamber because those like Honda and Mitsubishi make 10 HP per lb of air.

So, when I'm looking at selecting a power adder, now I can use a smaller, more compact and efficient blower or compressor wheel.